Tissues 10 - Skin

Question 1

What is the skin?

Answer 1

The skin is a single organ which has complex interelationships with other organ systems.

Question 2

List the functions of the skin.

Answer 2

• Protection against injury and against pathogenic organisms
• Waterproofing
• Thermoregulation
• Protection against radiation, vitamin D production
• Surface for grip
• Cosmetic

Question 3

Describe the basic structure of the skin.

Answer 3

• Top layer is the epidermis, then the dermis, then the hypodermis/subcutis.
• Skin contains apendigeal structures such as te pilo-sebaceous unit, which consists of the follicle sebaceous gland and pilo erecti muscle, and sweat glands

Question 4

What are the two types of sweat glands in the skin?

Answer 4

• Apocrine sweat glands secrete sweat indirectly via the hair follicle, present in the hair at the armpits and the pubic region. Sweat is thicker and smellier.
• Eccrine sweat glands secrete sweat directly to the skin, this sweat is thinner and less smelly

Question 5

Describe the structure of the epidermis, in relation to the keratinocytes.

Answer 5

The epidermis contains 4 layers of keratinocytes.

• Stratum basale (bottom)
• Stratum spinosum
• Stratum granulosum
• Stratum corneum (top)

Question 6

What cells, other than the keratinocytes, are present in the epidermis?

Answer 6

• Melanocytes (produce melanin)
• Langerhans cells (antigen presenting)
• Merkel cell (sensation)

Question 7

Describe the process of melanin production.

Answer 7

• Melanocytes produce melanin in the melanosomes (an organelle), and package it in granules.
• The granules are then transferred to adjacent heratinocytes by dendritic processes.
• Melanocytes are stimulated to produce melanin in UV light to form a cap around the nuceli of keratinocytes, preventing DNA damage.

Question 8

Describe the structure of the basement membrane zone of the skin.

Answer 8

The basement membrane zone attaches the epidermis to the dermis by hemi-desmosomes, anchoring plaques and proteins.

Question 9

Why is the basement membrane zone of the skin important clinically?

Answer 9

Damage fives rise to a blistering condition, such as epidermolysis bullosa.

Question 10

Describe the structure of the dermis.

Answer 10

• A supportive connective tisses consisting of collagen, elastin and glycosaminoglycans.
• 0.1mm (eyelids) to 3mm (back)
• Contains fibroblasts
• Contains dendritic cells

Question 11

What is present in the hypodermis of skin?

Answer 11

It is a subcutaneous layer - contains connective tissue and fat.